Structural and electrical characterizations of BiFeO3 capacitors deposited by sol–gel dip coating technique

Abstract

Bismuth ferrite (BiFeO3) thin films were deposited by sol–gel dip coating (SGDC) technique on Si-P(100) and glass substrates to investigate the structural and electrical characteristics. The aluminum (Al) metal contacts were formed on the samples deposited on the Si-P(100) to fabricate metal-oxide-semiconductor (MOS) capacitors. The fabricated MOS structures were characterized electrically by capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. The structural characterizations were performed by X-ray diffraction technique and scanning electron microscopy. The compositions of the films were investigated by energy-dispersive X-ray spectroscopy. The results exhibit that pure rhombohedral perovskite phase films were fabricated without any elemental contamination. Average grain sizes of the BiFeO3 deposited on silicon and glass wafers were found to be about 34,50 and 30,00nm, respectively. In addition, while the thin films deposited on glass substrate exhibit porous surface, those deposited on Si-P(100) wafers exhibit dense microstructure with a homogenous surface. Moreover, the C–V and G/ω–V characteristics are sensitive to applied voltage frequency due to frequency dependent charges (Nss) and series resistance (Rs). The peak values of Rs have been decreased from 2,6kΩ to 40Ω, while Nss is varied from 6,57×1012 to 3,68×1012eV−1cm−2 with increasing in frequency. Consequently, pure phase polycrystalline BiFeO3 thin films were fabricated successfully by SGDC technique and BiFeO3 dielectric layer exhibits stable insulation characteristics.